Flexible resistive NO2 gas sensor of SnO2@Ti3C2Tx MXene for room temperature application

SnO2 nanoparticles@Ti3C2Tx MXene have been successfully synthesized by a flexible solvothermal method. The Ti3C2Tx MXene was evenly anchored by the SnO2 nanoparticles (∼5 nm) through the controllable assembly heterojunction. Ti3C2Tx MXene contributed to the improvement of material conductivity compared to SnO2 nanoparticles. The combination of SnO2@Ti3C2Tx exhibits excellent sensitivity and selectivity to NO2 at room temperature (RT). Compared with pure Ti3C2Tx MXene, the sensitivity of TCS1.5 nanocomposite increases more than 20 times to 300 ppm NO2 at RT. In order to explore the sensing mechanism of SnO2@Ti3C2Tx nanocomposite to NO2, nitrogen adsorption-desorption isotherm technology and DFT calculations were performed. They demonstrated that the high specific surface area, well-proportioned heterogeneous structure of SnO2@Ti3C2Tx MXene, and the vital ionic bonds of Sn–N and O–N formed between substrate and NO2 gas had beneficial effect on improving the gas response capability.